Two Herens cows lock horns during the qualification round of the annual “Battle of the Queens” cow fight finals in Aproz, in the western Alpine canton of Valais May 5, 2013. Each year when taken to the alpine pastures, the cows test their strength and fight for the herd's leadership. The competition continues until a new queen has forced all the other cows to retreat. (Photo by Valentin Flauraud/Reuters)

A brown capuchin monkey holds a fruit in the Botanic Garden of Rio de Janeiro, Brazil, on July 5, 2013. (Photo by Pablo Porciuncula/AFP Photo)

Karis, a one month old lion cub being weighed at Blair Drummond Safari Park near Stirling, Scotland, Thursday October 10, 2013. Weighing in at 5kg, the cub will stay with her mother, Teekay until she is 12 weeks old before they are returned to the pride. (Photo by Andrew Milligan/AP Photo/PA Wire)

Let the fun begin. Revellers carry their belongings as they arrive at Worthy Farm in Somerset for the Glastonbury Festival, Britain, June 22, 2016. Around 180,000 are expected to attend. (Photo by Ben Birchall/PA Wire)

Natasha Hastings of U.S. on the starting block before the women's 400 metres heats during the 15th IAAF World Championships at the National Stadium in Beijing, China August 24, 2015. (Photo by Lucy Nicholson/Reuters)

A devotee of the Chinese Jui Tui Shrine has his face pierced with metal rods during a street procession during the annual Vegetarian Festival in the southern Thai town of Phuket on October 19, 2015. During the festival, which begins on the first evening of the ninth lunar month and lasts nine days, religious devotees slash themselves with swords, pierce their cheeks with sharp objects and commit other painful acts to purify themselves, taking on the sins of the community. (Photo by Nicolas Asfouri/AFP Photo)

“Misty Morning”. Every morning, people expect sunny weather. Photo location: Bali, Indonesia. (Photo and caption by Henry Adam/National Geographic Photo Contest)

A riot policeman uses a baton to hit a rioting University of Nairobi student in Kenya's capital Nairobi, in this May 20, 2014 file photo. (Photo by Noor Khamis/Reuters)